Method of growing large-diameter dislocation-free &lt;110&gt; crystalline ingots

ABSTRACT

A method of growing a crystalline ingot having a &lt;110&gt; orientation, such as a dislocation-free (“DF”) crystalline ingot, is provided. The method of manufacture includes providing a liquidous melt. Next, a seed crystal having a &lt;110&gt; crystal direction is contacted with the surface of the melt. The seed crystal is then withdrawn from the melt to thereby grow a neck. According to one embodiment, the seed elevation rate is automatically modified during the withdrawing step to reduce the diameter of the neck to greater than about 2.5 mm. Thereafter, the seed elevation rate is manually modified to alternate the diameter of the neck between about 2 mm and about 2.5 mm to thereby shape the neck into a recurring hourglass configuration. The neck is then withdrawn from the melt to grow a crystalline ingot having a &lt;110&gt; crystal direction and a diameter of at least about 200 mm.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional of U.S. application Ser. No.09/778,373, filed Feb. 7, 2001, which is hereby incorporated herein inits entirety by reference.

FIELD OF THE INVENTION

[0002] The present invention relates generally to a method of growingcrystalline ingots and, more particularly, to a method of growinglarge-diameter, substantially dislocation-free crystalline ingots havinga <110> crystal direction.

BACKGROUND OF THE INVENTION

[0003] The monocrystalline silicon that is the starting material formany semiconductor electronic components is commonly prepared by aCzochralski (“CZ”) process. In this process, pieces of polycrystallinesilicon are placed in a crucible and melted to a liquidous state,thereby creating a melt. A seed crystal having the desiredmonocrystalline atomic structure is then lowered into contact with themolten silicon. As the seed crystal is slowly extracted from the melt, amonocrystalline ingot is drawn from the melt having the same atomicstructure as the seed crystal.

[0004] Unfortunately, dislocation defects are generated in the seedcrystal due to the thermal shock created as the seed crystal contactsthe melt. Unless corrective actions are taken, the dislocation defectscan propagate through and multiply in the growing crystal. As known tothose skilled in the art, dislocations generally propagate alongcrystallographic planes. For a silicon seed crystal having a <100>crystal direction, the dislocations typically propagate along a planethat extends at an angle of 55° from the longitudinal axis of thecrystal. For a silicon seed crystal having a <110> crystal direction,the dislocations typically propagate along a plane that extends at anangle of 54.74° from the longitudinal axis of the crystal or propagatealong the growth axis itself.

[0005] In order to terminate the dislocations prior to propagationthrough the main body of the crystalline ingot, crystals are typicallygrown with a neck section extending between the seed crystal and themain body of the crystal. The most common method of eliminatingdislocations is known as the Dash method and involves growing a neckhaving a relatively small diameter and a relatively long length. Forexample, for a crystalline ingot having a <100> crystal direction, aneck grown according to the Dash method may have a diameter of between 2mm and 4 mm and a length between 30 mm and 200 mm. As the neck is grown,the dislocations propagate through the neck toward the interface of theseed crystal and the melt. As a result of the extended length and smalldiameter of the neck, however, the dislocations terminate at theexterior surface of the neck such that the main body of the crystal isdislocation free (“DF”). The crystal is then expanded in diameterthrough the shoulder or cone portion to the DF main body. Since there isno easy and reliable method to determine if the dislocations have beenterminated, the Dash method generally requires the neck to have arelatively small diameter and an extended length in order to effectivelyterminate most, if not all, dislocations.

[0006] Although the Dash method is widely utilized to growlarge-diameter crystalline ingots having a <100> orientation, includingingots having diameters exceeding 200 mm, the growth of large-diameterDF crystalline ingots having a <110> orientation has been limited toingots having a diameter of less than approximately 155 mm. Crystalshaving a <110> orientation are more difficult to grow than crystalshaving a <100> orientation because dislocations in <110> crystals canpropagate along the growth axis, resulting in a crystal having no usablematerial. In addition, the thin neck grown according to the Dash methodlimits the crystal length and weight.

[0007] DF crystalline ingots having a <110> orientation are particularlydesirous because such ingots have an improved wafer oxidation rate overcrystalline ingots having a <100> orientation and an improved surfacestate density and Epi-pattern displacement over crystalline ingotshaving a <100> orientation. Thus, a need exists for an improvedtechnique for growing large-diameter DF crystalline ingots having a<110> crystal direction and, in particular, a technique for growing DFcrystalline ingots having a <110> crystal direction and a diameter ofapproximately 200 mm and larger.

SUMMARY OF THE INVENTION

[0008] The present invention provides a DF crystalline ingot having a<110> crystal direction and a diameter of at least about 200 mm and anassociated method of manufacture. More specifically, the presentinvention provides a monocrystalline ingot formed of silicon in whichthe crystalline ingot has a <110> crystal direction and a diameter of atleast about 200 mm. In one embodiment, the crystalline ingot is dopedwith phosphorous, arsenic, antimony, boron, aluminum, gallium, orindium. In another embodiment, the crystalline ingot includes a bodyportion and a neck extending therefrom. Advantageously, at least aportion of the neck adjacent to the body portion has a recurringhourglass configuration to thereby facilitate termination ofdislocations within the neck. The portion of the neck defining therecurring hourglass configuration preferably has a diameter alternatingbetween about 2 mm and about 2.5 mm.

[0009] The present invention also provides a method of manufacturing aDF crystalline ingot, including providing a liquidous melt. In oneembodiment, a seed crystal having a <110> crystal direction and a lengthof about 100 mm to about 120 mm is provided. In another embodiment, aseed crystal having a <110> crystal direction and a width of about 15 mmis provided. Next, the seed crystal is contacted with the surface of themelt. In one embodiment, the seed crystal is positioned near the meltprior to the contacting step to thereby raise the temperature of theseed crystal. In another embodiment, the seed crystal is held in contactwith the melt after the contacting step until the temperature of theseed crystal stabilizes. In still another embodiment, a portion of theseed crystal is inserted into the melt after the contacting step suchthat the inserted portion of the seed crystal melts. For example, in oneembodiment, a portion of the seed crystal about 1 mm to about 10 mm inlength is inserted into the melt.

[0010] The seed crystal is then withdrawn from the melt to thereby growa neck. Thereafter, the neck is withdrawn from the melt to grow acrystalline ingot having a <110> crystal direction and a diameter of atleast about 200 mm. In one embodiment, the seed elevation rate isautomatically modified during the first withdrawing step to reduce thediameter of the neck to greater than about 2.5 mm. Thereafter, the seedelevation rate is manually modified to alternate the diameter of theneck between about 2 mm and about 2.5 mm to thereby shape the neck intoa recurring hourglass configuration. Advantageously, the portion of theneck having the recurring hourglass configuration facilitatestermination of dislocations within the neck such that the crystallineingot grown during the second withdrawing step is substantiallydislocation free. The crystalline ingot preferably includes a shoulder,main body, and an elongate tail portion. In one embodiment, thetemperature of the melt is modified during the second withdrawing stepto flatten the cone portion of the crystalline ingot.

[0011] In another embodiment of the present invention, the seed crystalis withdrawn from the melt to thereby grow a neck having a first portionand a second portion. The first portion of the neck has a diameter thattapers from the diameter of the seed crystal. The second portion of theneck has a diameter alternating between about 2 mm and about 2.5 mm andhas a recurring hourglass configuration. Advantageously, substantiallyall dislocations are terminated within the second portion of the neck.In one embodiment, the seed elevation rate is automatically modifiedduring the withdrawing step to form the first portion of the neck.Thereafter, the seed elevation rate is manually modified to form thesecond portion of the neck. The second portion of the neck is thenwithdrawn from the melt to grow a crystalline ingot having a <110>crystal direction and a diameter of at least about 200 mm.

[0012] Accordingly, there has been provided an improved technique forgrowing large-diameter DF crystalline ingots having a <110> crystaldirection. Advantageously, the technique allows DF crystalline ingotshaving a <110> crystal direction and a diameter of at least about 200 mmto be grown.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a schematic side view illustrating one embodiment of aCZ crystal growing apparatus that can implement the method of thepresent invention;

[0014]FIG. 2 is a side view illustrating the seed crystal being movedinto contact with the melt;

[0015]FIG. 3 is a schematic side view illustrating the seed crystalbeing inserted or dipped into the liquified melt;

[0016]FIGS. 4a-4 d are sequential schematic side views illustrating thewithdrawal of the seed crystal from the melt to thereby grow a DFcrystalline ingot having a <110> crystal direction, according to oneembodiment of the present invention;

[0017]FIG. 5 is a side elevation view illustrating the neck formed bywithdrawing the seed crystal from the melt as shown in FIGS. 4a-4 b; and

[0018]FIGS. 6a-6 b are flow charts illustrating operations performedduring fabrication of a DF crystalline ingot having a <110> orientation,according to two advantageous embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention now will be described more fullyhereinafter with reference to the accompanying drawings, in whichpreferred embodiments of the invention are shown. This invention may,however, be embodied in many different forms and should not be construedas limited to the embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art. Like numbers refer to like elements throughout.

[0020] Referring to the drawings, and in particular to FIG. 1, there isillustrated a schematic of one embodiment of an apparatus 12 for growingcrystalline ingots using the CZ method. During crystal growingoperations, the seed crystal 10 is initially attached to a seed chuck 14that securely holds the seed crystal throughout the growth process. Forpurposes of illustration and not limitation, a typical seed crystal canrange from about 100 mm to about 120 mm in length, and more preferablyabout 110 mm in length, and have a cubic cross section of about 15 mm byabout 15 mm. In order to grow a crystalline ingot having a <110> crystaldirection, the seed crystal also has a <110> orientation. The seed chuckis connected to a rotatable cable or shaft 16 attached to a mechanism 18for lowering and raising the seed crystal relative to a melt 20, such asa molten bath of silicon. Preferably, the lowering and raising mechanism18 is in electrical and operable communication with a computing means 18a, such as a microprocessor, computer, or controller operating undersoftware control. As known to those skilled in the art, the melt mayinclude a predetermined percentage of dopant, if so desired, includingphosphorous, arsenic, antimony, boron, aluminum, gallium, or indium.Among other components, the growing apparatus 12 typically includes aheat insulator 22 and a heater 24 disposed concentrically within afurnace body 26. A bottomed cylindrical quartz crucible 28 is typicallyreceived or nested within a graphite susceptor 30 that is fixed at thetop end of a rotary shaft 32 that extends through the center of thefurnace body. A second heater 34 may be positioned below the crucibleand susceptor.

[0021] As illustrated in FIG. 1, the seed crystal 10 is secured withinthe seed chuck 14 and initially lowered to a position spaced from, butnear the surface of the melt 20. As described in block 54 of FIG. 6a,the seed crystal 10 is held in this position near the surface of themelt 20 so that the seed crystal warms by thermal convection andradiation to a temperature near the temperature of the surface of themelt. Preferably, the seed crystal 10 and the melt 20 are rotated inopposite directions so that the seed crystal warms evenly. In oneembodiment, the seed crystal 10 is held approximately 10 mm above thesurface of the melt 20. However, the seed crystal 10 can be spaced byother distances from the melt 20 so long as the seed crystal is warmedto a temperature near the temperature of the surface of the melt withoutdeparting from the spirit and scope of the present invention.

[0022] In one embodiment, the crystal is grown using an “ECZ” techniquedeveloped by the assignee of the present application in which anelectric potential is applied to the quartz crucible 28 filled with thesilicon melt 20. Not intending to be limited or bound to any particularexplanation or theory, it is believed that the electric potentialuniformly devitrifies the inner layer of the quartz crucible 28 to amostly B-cristobalite surface and that the uniform devitrificationreduces the occurrence of localized small B-cristobalite formations.Since the B-cristobalite is more resistant to dissolution than amorphousquartz, the inner surface of the crucible 28 becomes more resistant toundercutting and releasing of small crystalline particles.Advantageously, without the presence of the crystalline particles, thelikelihood of producing a dislocation-free crystal in the crucible 28increases. See commonly owned U.S. patent application Ser. No.09/362,103 entitled “Method of Manufacturing Crystal of Silicon Using AnElectric Potential” for a more detailed discussion of the ECZ technique.

[0023] As illustrated in FIG. 2 and as described in block 56 in FIG. 6a,once the seed crystal 10 reaches a stable temperature near thetemperature of the surface of the melt 20, the seed crystal is againlowered such that the end 10 a, i.e., the bottom surface, of the seedcrystal contacts the surface of the melt. The time necessary for theelongate seed crystal 10 to stabilize is dependent upon a number offactors, for example, the size of the melt, the temperature of the melt,the cooling gas flow rate, the weight of the charge, the location of theheaters, as well as the pressure in the growing apparatus, which isnormally maintained below ambient pressure. As the seed crystal 10contacts the melt 20, heat transfer from the surface of the melt to theseed crystal changes from primarily convection to primarily conduction.

[0024] The thermal shock arising from the change in the heat transfermechanism from convection to conduction results in dislocations beinggenerated in the seed crystal 10. As known to those skilled in the art,a seed crystal 10 having a predetermined orientation or crystaldirection defines one or more crystallographic planes along which thedislocations generally propagate. In particular, it is generallyunderstood that the dislocations tend to propagate along thecrystallographic plane of the seed crystal that is the most dense,although some dislocations may propagate along other crystallographicplanes. For a monocrystalline silicon seed crystal having a <110>orientation, the dislocations generally propagate along the {111} plane,which is disposed at an angle of approximately 54.74° relative to thelongitudinal axis 11 defined by the seed crystal 10, or parallel to the{110} plane itself, which comprises the growth axis.

[0025] As described in block 58 of FIG. 6a, the seed crystal 10 is heldin contact with the surface of the melt 20 until the temperature of theseed crystal stabilizes. Following the initial thermal shock, thetemperature of the entire seed crystal 10 quickly stabilizes to atemperature at or near the temperature of the surface of the melt so asto prevent any further dislocation generation. As illustrated in FIG. 3and described in block 60 of FIG. 6a, once the temperature of the seedcrystal 10 has stabilized as a result of primarily conductive heattransfer with the surface of the melt 20, the bottom end 10 a of theseed crystal may be further lowered and inserted into the melt. The end10 a of the seed crystal is inserted into the melt such that the entiredip portion 10 b of the seed crystal and all the dislocations containedtherein are liquified into the melt 20, becoming part of the moltenbath. As an example, and not for purposes of limitation, the dip portionof the seed crystal preferably ranges in length from about 1 mm to about10 mm, although other lengths, greater or smaller, are considered to bewell within the scope and spirit of the present invention. Once again,the seed crystal 10 is then held in position until the temperature ofthe seed crystal stabilizes.

[0026] As illustrated in FIGS. 4a-4 b and as described in block 62 ofFIG. 6a, once the temperature of the seed crystal 10 has stabilized andthe dip portion 10 b of the seed crystal has melted, the seed crystal isgradually withdrawn from the melt 20 to grow a neck 40. The seed crystal10 is withdrawn from the melt by gradually lifting the seed crystal fromthe surface of the melt using a lowering and raising mechanism 18, as isknown to those skilled in the art. As the seed crystal 10 is withdrawn,however, the seed crystal remains in contact with the melt 20 during theformation of the neck 40. The melt 20 and the seed crystal 10 aregenerally rotated in opposite directions as the seed crystal iswithdrawn from the melt to further improve the properties of theresulting crystal. For purposes of illustration and not limitation, thecrucible 28 and seed crystal 10 are rotated in opposite directions atapproximately 16 rotations per minute according to one embodiment.However, the seed crystal 10 and crucible 28 can be rotated at higher orlower speeds without departing from the spirit and scope of the presentinvention.

[0027] In one embodiment, as illustrated in FIGS. 4a and 5 and asdescribed in block 72 of FIG. 6b, the neck 40 preferably defines firstand second portions 40 a, b. As described in block 74 of FIG. 6b, thefirst portion 40 a of the neck 40 is formed by automatically modifyingthe seed elevation rate using the controlling means 18 a and raisingmechanism 18 to gradually reduce or taper the diameter of the neck fromthe diameter of the seed crystal 10. In this regard, the diameter of theneck 40 is proportional to the seed elevation rate such that an increasein the seed elevation rate reduces the diameter of the neck and adecrease in the seed elevation rate increases the diameter of the neck.For example, in one embodiment the seed elevation rate is automaticallyincreased from about 4 to about 5 mm per minute over a period of about45-55 minutes to thereby gradually taper the diameter of the neck 40 toan amount greater than about 2.5 mm over a length of approximately 22cm, see block 64 of FIG. 6a and block 72 of FIG. 6b.

[0028] As illustrated in FIGS. 4b and 5 and as described in block 76 ofFIG. 6b, the second portion 40 b of the neck 40 is formed by manuallymodifying the seed elevation rate using the raising mechanism 18 toalternate the diameter of the neck between about 2 mm and about 2.5 mmto thereby form an hourglass configuration 41. As noted above, thediameter of the neck 40 is proportional to the seed elevation rate suchthat an increase in the seed elevation rate reduces the diameter of theneck and a decrease in the seed elevation rate increases the diameter ofthe neck. According to one embodiment, the seed elevation rate isalternated between approximately 0 mm per minute and 5 mm per minute tothereby form an hourglass configuration 41 over a length of about 2.5 cmto about 3.0 cm, see block 66 of FIG. 6a and block 76 of FIG. 6b.Advantageously, substantially all of the dislocations are terminatedwithin the second portion 40 b of the neck 40. While not intending to belimited or bound to any particular theory or explanation, it is believedthat the combination of the hourglass configuration 41 and the reductionin diameter to between about 2 mm and about 2.5 mm effectivelyterminates dislocations within a neck 40 formed from a seed crystalhaving a <110> orientation.

[0029] As illustrated in FIGS. 4c-4 d and as described in blocks 68 and78 of FIGS. 6a and 6 b, respectively, once all of the dislocations areterminated within the neck 40, the second portion 40 b of the neck iswithdrawn from the melt 20 to grow a crystalline ingot according toconventional CZ crystal growing techniques. The second portion 40 b ofthe neck 40 is withdrawn from the melt by gradually lifting the neckfrom the surface of the melt 20. As the second portion 40 b of the neck10 is withdrawn, however, the neck remains in contact with the melt 20during the formation of the shoulder 42 and the main body 44 of thecrystal. As is known to those skilled in the art, the melt 20 and theneck 40 are generally rotated in opposite directions as the neck iswithdrawn from the melt to further improve the properties of theresulting crystal. In one embodiment, as described in blocks 70 and 80of FIGS. 6a and 6 b, respectively, the temperature of the melt 20 ismodified when withdrawing the neck from the melt to flatten the coneportion 42 of the crystalline ingot to thereby quickly increase thediameter of the cone portion and the resulting crystalline ingot.

[0030] The present invention also provides a method of manufacturing DFcrystalline ingots having a <110> crystal direction and a diameter of atleast about 200 mm. As described in FIG. 6a, the method of growing theDF crystalline ingots includes providing a liquidous melt. See block 48.In one embodiment, a seed crystal having a <110> crystal direction and alength of about 100 mm to about 120 mm is provided. See block 50. Inanother embodiment, a seed crystal having a <110> crystal direction anda width of about 15 mm is provided. See block 52. Next, the seed crystalis contacted with the surface of the melt. See block 56. In oneembodiment, the seed crystal is positioned near the melt prior to thecontacting step to thereby raise the temperature of the seed crystaland, thus, decrease the temperature gradient between the seed crystaland the melt. See block 54. In another embodiment, the seed crystal isheld in contact with the melt after the contacting step until thetemperature of the seed crystal stabilizes. See block 58. In stillanother embodiment, a portion of the seed crystal is inserted into themelt after the contacting step such that the inserted portion of theseed crystal melts. See block 60. For example, in one embodiment, aportion of the seed crystal about 1 mm to about 10 mm in length isinserted into the melt.

[0031] As illustrated in FIG. 6a, the seed crystal is then withdrawnfrom the melt to thereby grow a neck. See block 62. In one embodiment,the seed elevation rate is automatically modified during the withdrawingstep to reduce the diameter of the neck to greater than about 2.5 mm.See block 64. Thereafter, the seed elevation rate is manually modifiedto alternate the diameter of the neck between about 2 mm and about 2.5mm to thereby shape the neck into a recurring hourglass configuration.See block 66. Advantageously, the portion of the neck having therecurring hourglass configuration facilitates termination ofdislocations within the neck such that the crystalline ingot grown usingthe neck is substantially dislocation free. Thereafter, the neck iswithdrawn from the melt to grow a crystalline ingot having a <110>crystal direction and a diameter of at least about 200 mm. See block 68.The crystalline ingot preferably includes a cone portion, a main body,and an elongate tapered tail. In one embodiment, the temperature of themelt is modified during the second withdrawing step, i.e., whenwithdrawing the neck from the melt to grow a crystalline ingot, toflatten the cone portion of the crystalline ingot. See block 70.

[0032] In another embodiment of the present invention, as illustrated inFIG. 6b, the seed crystal is withdrawn from the melt to thereby grow aneck having a first portion and a second portion. See block 72. Thefirst portion of the neck has a diameter that tapers from the diameterof the seed crystal. The second portion of the neck has a diameteralternating between about 2 mm and about 2.5 mm and has a recurringhourglass configuration. Advantageously, substantially all dislocationsare terminated within the second portion of the neck. In one embodiment,the seed elevation rate is automatically modified during the withdrawingstep to form the first portion of the neck. See block 74. Thereafter,the seed elevation rate is manually modified to form the second portionof the neck. See block 76. The second portion of the neck is thenwithdrawn from the melt to grow a crystalline ingot having a <110>crystal direction and a diameter of at least about 200 mm. See block 78.As discussed above, the crystalline ingot preferably includes a shoulderor cone portion, a main body, and an elongate tapered tail. In oneembodiment, the temperature of the melt is modified during the secondwithdrawing step, i.e., when withdrawing the neck from the melt to growa crystalline ingot, to flatten the shoulder of the crystalline ingot.See block 80.

[0033] Accordingly, there has been provided an improved technique forgrowing large-diameter DF crystalline ingots having a <110> crystaldirection. Advantageously, the technique allows DF crystalline ingotshaving a <110> crystal direction and a diameter of at least about 200 mmto be grown. Many modifications and other embodiments of the inventionwill come to mind to one skilled in the art to which this inventionpertains having the benefit of the teachings presented in the foregoingdescriptions and the associated drawings. Therefore, it is to beunderstood that the invention is not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

That which is claimed:
 1. An article of manufacture, comprising: amonocrystalline ingot formed of silicon, said crystalline ingot having a<110> crystal direction and a diameter of at least about 200 mm.
 2. Anarticle according to claim 1 wherein said crystalline ingot is dopedwith a material selected from a group consisting of phosphorous,arsenic, antimony, boron, aluminum, gallium, and indium.
 3. An articleaccording to claim 1 wherein said crystalline ingot comprises a bodyportion and a neck extending therefrom, at least a portion of said neckadjacent to said body portion having a recurring hourglassconfiguration.
 4. An article according to claim 3 wherein said portionof said neck having a recurring hourglass configuration has a diameteralternating between about 2 mm and about 2.5 mm.
 5. An article ofmanufacture, comprising: a monocrystalline ingot formed of silicon, saidcrystalline ingot being substantially dislocation free and having a<110> crystal direction and a diameter of at least about 200 mm.
 6. Anarticle according to claim 5 wherein said crystalline ingot is dopedwith a material selected from a group consisting of phosphorous,arsenic, antimony, boron, aluminum, gallium, and indium.
 7. An articleaccording to claim 5 wherein said crystalline ingot comprises a bodyportion and a neck extending therefrom, at least a portion of said neckadjacent to said body portion having a recurring hourglassconfiguration.
 8. An article according to claim 7 wherein said portionof said neck having a recurring hourglass configuration has a diameteralternating between about 2 mm and about 2.5 mm.
 9. A crystalline ingotmanufactured by a process comprising the steps of: providing a liquidousmelt; contacting a seed crystal having a <110> crystal direction withthe surface of the melt; withdrawing the seed crystal from the melt tothereby grow a neck; and withdrawing the neck from the melt to grow acrystalline ingot having a <110> crystal direction and a diameter of atleast about 200 mm.
 10. A process according to claim 9, furthercomprising: automatically modifying the seed elevation rate during saidfirst withdrawing step to reduce the diameter of the neck to greaterthan about 2.5 mm; and thereafter, manually modifying the seed elevationrate to alternate the diameter of the neck between about 2 mm and about2.5 mm to thereby shape the neck into a recurring hourglassconfiguration.
 11. A process according to claim 9 wherein thecrystalline ingot comprises a cone portion, main body, and tail, andfurther comprising reducing the temperature of the melt during saidsecond withdrawing step to flatten the cone portion of the crystallineingot.
 12. A process according to claim 9 further comprising positioningthe seed crystal near the melt to thereby raise the temperature of theseed crystal prior to said contacting step.
 13. A process according toclaim 9 further comprising holding the seed crystal in contact with themelt after said contacting step until the temperature of the seedcrystal stabilizes.
 14. A process according to claim 9 furthercomprising inserting a portion of the seed crystal into the melt aftersaid contacting step such that the inserted portion of the seed crystalmelts.
 15. A process according to claim 14 wherein said inserting stepcomprises inserting a portion of the seed crystal about 1 mm to 10 mm inlength.
 16. A process according to claim 9 further comprising providinga seed crystal about 100 mm to about 120 mm in length prior to saidcontacting step.
 17. A process according to claim 9 further comprisingproviding a seed crystal having a width of about 15 mm prior to saidcontacting step.
 18. A process according to claim 9 wherein said firstwithdrawing step comprises withdrawing the seed crystal from the melt tothereby grow a neck having a first portion and a second portion, thefirst portion of the neck having a tapered diameter, the second portionof the neck having a diameter alternating between about 2 mm and about2.5 mm and having a recurring hourglass configuration.